Porous Coodination Networks for Artificial Photosynthesis

Photosynthetic systems consist of light harvesting arrays and redox mediators that can funnel the electrochemical potential stored in a molecular excited state to catalytic centers to drive the oxidation of water and the reduction of CO₂ to sugars. Many artificial approaches to this chemistry have been reported. Herein, we investigate porous coordination networks (PCNs) as both light harvesters and high surface area catalysts as photosynthetic mimics. PCNs combine the synthetic diversity possible with molecular catalysts and the ease of recovery of heterogeneous catalysis. Theoretically, the high surface area of PCNs can be exploited to produce a higher catalytic rate per geometric area than those realized by other approaches. Additionally, the incorporation of molecular chromophores into networks has been show to lead to enhanced luminescence quenching. We report the effects of network incorporation on homo-resonance energy transfer between molecular chromophores incorporated into a water stable PCN. Additionally, the mechanism of electron transport through PCNs is discussed. Lastly, PCNs capable of driving water oxidation and CO₂/H⁺ reduction are presented.